class ImapServer
  # Handle one client socket
  class ClientHandler
    Dir["lib/imap_server/client_handler/*.rb"].each do |mod|
      mod_name = File.basename(mod, ".rb")
      require_relative "client_handler/#{mod_name}"
      include const_get(mod_name.capitalize)
    end

    def initialize(server:, socket:)
      @server = server
      @socket = socket
    end

    # write something to the client
    def write(*messages)
      if messages.size == 1
        raw_message = messages.first.to_s
        $logger.debug "S: #{raw_message.chomp}"
        @socket.write raw_message
      else
        messages.each { write(_1) }
      end
    end

    # read the socket and return the next client message
    def read
      input = @socket.gets if !@socket.closed?
      input&.chomp!
      $logger.debug "C: #{input}"
      input
    end

    def greeting
      write ServerMessage.new("OK IMAP4rev1 AUTH=PLAIN server ready")
    end

    # Start a new imap connection
    def start
      greeting

      loop do
        client_input = read
        break if client_input.nil?

        process(client_input)
      end
    end

    # Handles ONE input from the client.
    # Handlement is done by delegating behavior of the command to external handler
    # loaded as modules.
    #
    # The handlers start as #handle_ followed with the command token downcased.
    # Handlers will receive the parser client message and the current user authenticated.
    # If needed, a reference to the current context is provided along with the client message
    # with msg#handler.
    def process(client_input)
      client_message = ClientMessage.parse(client_input).with(self)
      handler_method = "handle_#{client_message.command}"
      if respond_to?(handler_method)
        send(handler_method, msg: client_message, user: @user)
      else
        write ServerMessage.new("KO Unhandled command \"#{client_message.command}\"", tag: client_message.tag)
      end
    rescue StandardError => e
      $logger.error e
    end

    # TODO: move this module
    module CommandHelpers
      attr_accessor :selected, :user

      def authentified?
        @user
      end

      def authenticate_user!(username:, password:)
        if (@user = User.authenticate(username: username, password: password))
          true
        else
          false
        end
      end
    end
    include CommandHelpers

  end
end